The present invention relates generally to fastener driving tools, and more specifically to such a tool having a pre-pressurized power delivery source.
Power tools for use in driving fasteners into workpieces are known in the art. Such tools can be operated by a variety of power sources, including pneumatic, combustion, electric or powder-activated power sources. In some power tools, the power source is integrated with a housing of the tool for easy portability. Other applications require power to be fed with a feed line from an external source, such as pneumatic tools operated by an air compressor.
Fastener driving tools of this type, and particularly pneumatically powered tools, include a gun-shaped metal housing and a magazine portion, which is attached to the housing and/or the handle. Generally, the magazine retains a supply of fasteners which are fed to a drive track in the housing adapted to receive a fastener and to guide the fastener as the fastener is driven from the drive track into a workpiece.
The housing also includes a piston in a main chamber of the fastener driving tool which is mounted for reciprocal movement along the chamber to be driven by compressed air, products of combustion, or otherwise from a retracted position to an extended position in a driving stroke. The driving stroke of the piston moves a driver blade in the drive track that impacts a fastener to drive the fastener into a workpiece. The piston is also configured to be oppositely driven by a return spring, a partial vacuum, or other known apparatus in a return stroke to the retracted position.
The use of existing fastener driving power tools has certain disadvantages. One disadvantage is that these tools are designed with a large number of components, any one of which can malfunction due to wear and tear in normal use. Additionally, costs for assembly, manufacture, and repair of these tools can be considerable. Another drawback associated with some existing fastener driving power tools is that they can be fatiguing to use on a continual basis due to their weight and bulkiness. Furthermore, some tools of this type require a power feed line, such as a compressed air hose, which is awkward to use since, in addition to the tool, the power feed line must be transported by the operator.
A portable pneumatic power tool is disclosed having a magazine to sequentially supply fasteners to a nosepiece of the tool for impacting into a workpiece. The tool has a housing having a reciprocating driver blade at least partially positioned within the housing. The driver blade is driven by a self contained pre-pressurized power delivery source preferably located in a vessel that is removably attached to the housing.
In an alternative embodiment, a trigger mechanism is disclosed for a fastener driving tool having a pre-pressurized power source and a magazine for storing and sequentially urging fasteners toward a nosepiece through which a driver blade travels to impact and drive the fasteners into a workpiece. The trigger mechanism has a valve-opening member, a valve, and a trigger. The valve is capable of being opened and closed by reciprocation or the valve-opening member, and controls a flow of a pressurized medium from the pre-pressurized power source. The trigger holds the valve-opening member in a set position until being actuated, which causes the valve-opening member to move in a lateral direction to open the valve and permitting a flow of the pressurized medium through the valve. The flow of the pressurized medium through the valve is limited to a fixed amount by the flow, which causes the valve-opening member to recoil to the set position and reset the trigger mechanism.